Electrochemically controlled solid-phase micro-extraction of proline using a nanostructured film of polypyrrole, and its determination by ion mobility spectrometry

We report on a fast, simple and accurate method for the determination of proline in urine samples by employing a nanostructured film of conducting polypyrrole for electrochemically controlled solid-phase microextraction, and ion mobility spectrometry (IMS) for detection. This method has the advantages of simple sample preparation and a sensitivity of IMS to proline that is higher than that for other amino acids. The calibration curve is linear in the range of 0.5-60 mu g L-1 (4-521 nmol L-1), and the detection limit is 0.2 mu g L-1. The electrochemical potentials for uptake and release were optimized. The method was successfully applied to the clean-up and quantitation of trace amounts of proline in urine samples.